1. Field of the Invention
The present invention relates to a driving circuit, and a liquid crystal display module having the same.
2. Description of the Related Art
An electronic display device displays information generated from various electronic devices as an image. Recently, electronic display devices have been developed to have a large size and a thin profile. Furthermore, as a chip on flexible printed circuit (COF) technology has been developed, the electronic display device has a thinner profile.
The COF is manufactured by mounting a semiconductor chip directly on a film type circuit board. The COF is advantageous in that a film which is thinner than that of a related art tape carrier package (TCP) may be used, and leads to which a signal is applied may be arranged at intervals shorter than those in the TCP.
FIG. 1 is a plan view illustrating a liquid crystal display (LCD) module employing the related art COF. FIG. 2A is an enlarged perspective view of part A′ of FIG. 1, and FIG. 2B is a cross-sectional view taken along line II-II′ of FIG. 1.
Referring to FIG. 1, a related art LCD module 501 includes a LCD panel 510 displaying an image. The LCD panel 510 includes driving circuits 600 for driving a display device therein. The driving circuits 600 are disposed on an edge of the LCD panel 510.
Each of the driving circuits 600 includes a substrate 630, a driving chip 610, and circuit lines 620. The driving chip 610 is disposed on the substrate 630 having a film shape, and the circuit lines 620 are electrically connected to the driving chip 610 disposed on the substrate 630.
The driving circuit 600 transmits a driving signal processed by a printed circuit board (PCB) to the LCD panel 510.
Referring to FIGS. 2A and 2B, the LCD panel 510 and the driving circuit 600 are electrically connected together by an anisotropic conductive film (ACF) 640.
The LCD panel 510 includes a plurality of thin film transistors (TFTs) (not illustrated) and pixel electrodes (not illustrated) connected to the TFTs. The TFT provides a pixel voltage to the pixel electrode in response to a driving signal applied from the driving circuit 600.
The LCD panel 510 includes signal lines 525 electrically connected to the thin film transistors, and pad portions 520 provided at respective ends of the signal lines 525 and electrically connected to the respective circuit lines 620 of the driving circuit 600. Each circuit line 620 of the driving circuit 600 overlaps each signal line 525 of the LCD panel, and the circuit line 620 and the signal line 525 are electrically connected together by the ACF 640. The ACF 640 includes fine conductive balls.
Since the related art driving circuit 600 is formed on the substrate 630 having the film shape, the driving circuit 600 is advantageous in that it can be bent or folded. Furthermore, since the driving circuit 600 can be folded or bent, the entire size of the LCD module 501 can be reduced.
However, when the driving circuit 600 is folded or bent, the circuit lines 620 formed on the driving circuit 600 may be damaged or cut.
FIG. 3A is a plan view illustrating a related art LCD module having a PCB, and FIG. 3B is an enlarged view of part ‘B’.
Referring to FIG. 3A, the LCD module 501 includes a plurality of driving circuits 600 on an edge of the LCD panel 510, and a PCB 700 electrically connected to the driving circuits 600.
The LCD panel 510 and the driving circuits 600, and the driving circuit 600 and the PCB 700 are electrically connected together by anisotropic conductive films, respectively. To attach the PCB 700 to the driving circuit 600 with the anisotropic conductive film, heat and pressure are applied to the anisotropic conductive film. Also, after the PCB 700 and the driving circuit 600 are attached, the PCB 700 is cooled. Thus, the PCB 700 electrically connected to the driving circuit 600 expands when electrically connected to the driving circuit 600, while it is heated, and contracts after the connection when it cools.
The expansion and contraction of the PCB 700 creates great stress at the LCD module 501, and cracks and damages may occur to the PCB 700 and the driving circuit 600 by such stress.
Otherwise, when vibration and impact are applied to the PCB 700 and/or the driving circuit 600, the PCB 700 and/or the driving circuit 600 may be easily damaged.